Aussie Chrysler hemi six

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I'd love to have one of these hemi sixes in an early Barracuda notchback! But for now I'm dealing with a daily driver with a little 4-cyl hemi that I have de-smogged and upgraded so that the factory timing curve is no longer suitable (and the vacuum advancer leaks and is NLA). I cleaned up the port, welded up tri-Y header, got rid of the plugged-up cats, the EGR, and the other smog crap, so that the cylinders should now fill better and clear out the exhaust residuals better. So I shouldn't need to start the fire as early.

Can one of you in Oz supply me with the timing advance specs, centrifugal and vacuum, for a pre-emissions hemi-six? Re-calibrating my dizzy to these specs ought to get me fairly close, my assumption being that a 2-valve hemi head with flat-top pistons, 8.6:1, and no squish/quench area, wants a somewhat different curve than a wedge engine. Of course, I'll fine-tune it on my "10% dyno", a road up a long hill with a 10% grade.

(Edit) I'm asking for hemi-six advance specs because I don't know of another small-bore pre-emissions hemi-head engine. One occurs to me now: the old Daimler sports car of around 1960 had a 2.5L V-8 hemi, IIRC. Maybe I can find a collector . . . .

(Edit2) Working on it. Found out that Daimler managed to build a 4.5L version of that same all-aluminum V8 hemi, somewhat de-tuned and used in luxury sedans in the mid-Sixties. THAT's likely the engine with advance specs near what I need.
 
I doubt if an advance curve for the Aussie hemi six would help much, in reality it wasnt a true hemi as such more like a cleveland canted valve setup.
Is the 4 cylinder some sort of Mitsubishi type of thing?
A7M
 
Toyote has a 2 valve hemi head 4 cyl 1970-1982
"2T", "2TC" ,"3TC"
Made them by the thousands in Corollas and Celicas that I know of. They may have used them in other models as well.
 
The Mazda / Ford Courier 4 was also a Hemi. Built one back in the early 80’s for my brother in law was de-smogged, ported the head and intake, Weber carb, mild cam, headers, MSD box, turbo muff & 2.5 exhaust. Was a decent runner.

Edit: build up was on a 1976 Ford Courier had a 5 speed
 
:) Yep,that 2TC Corolla was a good little engine.Bought a NEW 1600 series Corolla in 71.Good performance and fuel economy.96.6CI,and 102HP IIRC.4 speed.
As a bit of an after thought,Tax,title and off the lot price.$1932.00
Leo
 
The trouble with most of those is that they were smog-era engines from the begining, with all systems including spark-timing calibrated for passing emissions tests. But how far back does the Peugeot hemi go? Well, for that matter, maybe all of the engines YOU guys in Oz had were not as "smogged" as ours. You see what I'm trying to get, a timing curve for a torquey, fuel efficient, but politically incorrect little hemi (Mitsu G63B, non-turbo, in an '87 Dodge Colt Vista 4wd micro-wagon)?
 
My Peugeots were mid sixties 403 and 404 pushrod two valve hemis but I have no idea of the piston shape. The 404 was a decent runner. There was a twin carb version in some 504s. Log style intake though.
 
Interesting article, Jack. But that's an aluminum prototype of what became our ordinary North American cast-iron Slant Six 170-198-225. The "Hemi Six" I mentioned was built by Chrysler of Australia; we never saw it. A strong performer even factory-stock, and a real giant-killer when somebody like Xecute/Deano sends one out of his shop. He PM'd me a couple of paragraphs on that engine a few years ago, which I saved (I'd save any info or advice the man chooses to favor me with!), and if he turns up for this discussion maybe he'll give his permission for me to paste it here. I HOPE he will make an appearance, because he likely has a manual with the timing curves for the Hemi Six, or his own, better, suggestions. A7M correctly points out that the Hemi Six was not really a hemi, but a non-crossflow polyspherical head, but I thought the advance specs still might be a place for me to start. I want to re-calibrate the weights/springs/vacuum-can on a distributor machine before I put it in the engine. I have specs that work well for any pre-smog, semi-performance smallblock Chev . . . .
 
Astoundingly, I turned up a Daimler RACER in England!! Russ Carpenter runs a 4.5 on fuel in a dragster chassis, turns low sevens at 170-180mph or something (Google "Russ Carpenter Racing"). I contacted him at russcarpenter@daimlerv8.co.uk. Here's his very prompt answer and my response:

(quote email)
Hello Phil

The Daimler figures are as follows : static timing 10 degrees BTC, centrifugal adv’ starts at 300 RPM at 7 ½ degrees up to 750 RPM, The max centri’ adv’ is11 ½ degrees at 2250 RPM. Vacuum adv’ starts at 6 inches and is maxed at 16 ½ inches at 9 degrees. This is distributer RPM

Regards RUSS



Thank you so much, Russ, especially for the nearly instant response!! Interesting figures; the vacuum advance is similar to other engines, but the centrifugal advance is a good deal less, at least less than wedge engines I've known. Hemi designs with low-ish compression (no big piston dome in the way) are supposed to take less advance according to what I read, but this seems like a LOT less. Any comments on this, or whether you think it applies to my de-smogged Mitsu hemi??

Thanks again,
(end quote)


(Edit) Double-checked; he's running a 2.5L!! 1500hp on 85% nitro, 7.20 at 179. Mercy!!
 
Yes your right. The sign of a more efficient combustion chamber is that it needs less total advance.
 
Here's what I got from a poster called "dieselgeek" who sounds like he might have experience with this engine in non-factory trim, at Speed Talk (good site). He says:

at idle, total timing around 15 degrees
light cruise, total no more than mid-30s (seems low to me, but I'm the one who's asking)
WOT, no more than 25-28 degrees


It's so far looking like I'd be somewhere near a place to start with this:

A bit less than the factory static timing, say 5 to 6 degrees,

Leave the factory centrifugal advance curve where it is for now,

Adapt a Chevy vacuum advancer to the factory dizzy. I bought one and checked it with a hand-pump: starts moving at about 5"Hg, all-in at about 12". That might be somewhere near okay although I returned the Chevy advancer and will get an adjustable aftermarket unit.

Again, this is just to get me on the road. Later on some all-electronic system, maybe Mega-Squirt, may be the way to go.

Thanks for the help.
-Smitty
 
I just wish dyno time wasn't so expensive. There's a thought!!!: anybody seen a good set of plans for a homebuilt dyno?


(Edit) Took a second to Google "DIY dyno" and got some hits; I'm going to take a look, anyway.
 
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